Do you want preteens or not *Note* (I do respect everyone opinion)

Instead of creating a new life stage. They could have it to where your sims new height overlaps between children and teens or toddler and kids. For example your children growing taller in the middle of their child life stage. They remain that same height until their growth spurt. Maybe they could acknowledge growing taller without it having to be their birthday.

I don't mind adults being the same height but I think children should have more heights to them. It would look better when you have lots of children in the household of supposedly different ages.